1. Field of the Invention
The present invention relates to an apparatus for relatively positioning a plurality of objects, for example, minute precision components such as semiconductor elements, by the use of a scanning optoelectric microscope.
2. Description of the Prior Art
A prior art optoelectric microscope has been constructed so that a division of an object to be measured is positioned to a reference slit or the center of oscillation of a slit provided within the microscope. With reference to FIG. 1, description will be made of the prior art optoelectric microscope with which the division of an object to be measured is positioned to the center of oscillation of the slit provided within the microscope. Numeral 1 designates a stand for an object to be measured, 2 the object to be measured, 3 a mark for the position detection as provided on the object to be measured, 4 an objective lens, 5 a source of light, and 6 a half mirror. A slit plate 7 is mounted on a vibrator 9, and is provided with a slit 8 at one end. Shown at 10 is a photoelectric element, which detects a reflected light image from the object to be measured 2 through the medium of the slit 8 and which outputs the detected image in the form of an electric signal. An amplifier circuit 11 amplifies the signal from the photoelectric element 10, and delivers its output signal to a phase detection circuit 13. Numeral 12 indicates a reference signal generator, which outputs a reference signal to the phase detection circuit 13 and the vibrator 9. The phase detection circuit 13 outputs to a motor driver circuit 14 a signal of the phase difference between the signal from the amplifier circuit 11 and the signal from the reference signal generator 12. A driving motor 15 moves the stand 1 for the object to be measured. The amount of drive of the motor 15 is controlled on the basis of an output signal from the motor driver circuit 14.
With the foregoing construction, light given out by the light source 5 impinges upon the position detecting mark 3 on the object to be measured 2, and is turned into reflected light on the position detecting mark 3. The reflected light leads to the slit 8 through the objective lens 4 and the half mirror 6. The vibrator 9 vibrates the slit plate 7 in synchronism with the reference signal from the reference signal generator 12. A change in the quantity of light of a light flux passing through the slit 8 provided in the slit plate 7 is detected by the photoelectric element 10, and is converted into the electric signal. The detection signal converted into the electric signal is transmitted via the amplifier circuit 11 to the phase detection circuit 13, and is phase detected therein by the reference signal from the reference signal generator 12. At this time, where the position detecting mark 3 deviates from the center of oscillation of the slit 8, a D.C. signal is outputted from the phase detection circuit 13. It drives the stand 1 for the object to be measured via the motor driver circuit 14 and by the driving motor 15, so as to adjust the position detecting mark 3 to the center of oscillation of the slit 8.
In the case of performing the relative positioning of a plurality of objects by the use of the optoelectric microscope, the centers of oscillations of a plurality of slits provided within the optoelectric microscope are made references, and the position detecting marks on the respective objects are separately adjusted thereto. Therefore, the positioning accuracy lowers. A further disadvantage is that since a plurality of detecting systems and driving systems are required for each positioning in one direction, the apparatus becomes complicated.